In CodeSniffer, a coding standard is basically represented by an empty class that extends PHP_CodeSniffer_Standards_CodingStandard. I could not get the CodeSniffer to find my coding standard, though, and found the documentation lacking about where to put it, how to name it, and how to refer to it in the --standard switch.

After an email to Greg Sherwood (developer of the package) Stefan figured out his issue and has shared the solution in this post (step by step).